In the realm of computer networking, promiscuous mode refers to the special mode of Ethernet hardware, in particular network interface cards (NICs), that allows a NIC to receive all traffic on the network, even if it is not addressed to this NIC. By default, a NIC ignores all traffic that is not addressed to it, which is done by comparing the destination address of the Ethernet packet with the hardware address (a.k.a. MAC) of the device. While this makes perfect sense for networking, non-promiscuous mode makes it difficult to use network monitoring and analysis software for diagnosing connectivity issues or traffic accounting.

In a wider sense, promiscuous mode also refers to network visibility from a single observation point, which doesn't necessarily have to be ensured by putting network adapters in promiscuous mode. Modern hardware and software provide other monitoring methods that lead to the same result. In this white paper, we'll discuss the techniques that are commonly used to ensure network visibility in different network environments, both wired and wireless, equipped with different kinds of hardware.